Oracle / PLSQL: COALESCE Function

This article is written about how to use the Oracle/PLSQL COALESCE function with syntax and examples.

Description

The Oracle/PLSQL COALESCE function returns the first non-null expression in the list. If all expressions evaluate to null, then the COALESCE function will return null.

Syntax

The syntax for the COALESCE function in Oracle/PLSQL is:

COALESCE( expr1, expr2, ... expr_n )

Parameters or Arguments

expr1, expr2, … expr_n

The expressions to test for non-null values. The expressions must all be the same datatype.

Returns

The COALESCE function returns returns any datatype such as a string, numeric, date, etc. (BUT all expressions must be the same datatype in the COALESCE function.)

If all expressions are not the same datatype, an ORA-00932 error will be returned.

Applies To

The COALESCE function can be used in the following versions of Oracle/PLSQL:

Oracle 12c, Oracle 11g, Oracle 10g, Oracle 9i

Example

The COALESCE function can be used in Oracle/PLSQL.

You could use the coalesce function in a SQL statement as follows:

SELECT COALESCE( address1, address2, address3 ) result
FROM suppliers;

The above COALESCE function is equivalent to the following IF-THEN-ELSE statement:

IF address1 is not null THEN
   result := address1;

ELSIF address2 is not null THEN
   result := address2;

ELSIF address3 is not null THEN
   result := address3;

ELSE
   result := null;

END IF;

The COALESCE function will compare each value, one by one.